okay, just throwing this out there. I blew up the van picture to see if the door was infact open. Maybe? I realize it is really blurry, sorry not super great with graphics. If it was a tree the dark black patch would extend to the ground, it doesn't you can clearly see the bottom white part of the fan. It looks too wide to be the ladder, it wouldn't show up a thick black patch more thinner with white in between the black parts.
Also, just throwing this out there as it hasn't been brought up (maybe b/c it is pretty far fetched) but who is to say that if things went bad and she died that it happened outside of the van or far away from the van (where he would have to carry a body). If this is the case he could've drove with her body inside the van and dumped it anywhere along the way back to Florida. Probably not likely but this case is so bizarre anything is possible.